The present invention relates to a method of controlling multi-layer welding operations in which a joint to be welded is subjected to multi-layer welding by an arc welding process employing a consumable electrode or a nonconsumable electrode with a filler wire.
It has been known in the past that when relatively thick metal plates are to be welded by butt welding, welding techniques, i.e., a multi-layer welding process is used in which a plurality of welding passes are repeated on a joint to be welded and the weld beads resulting from the respective passes are deposited one after another in a number of layers within the groove to be welded. In this case, if the joint has a bevel angle, as the deposition of layers proceeds, the groove which for the following layer is increased and the number of passes for the following layer must be increased correspondingly. The reason is that the maximum bead width which can be applied by a single pass is limited from the standpoint of ensuring the desired welded joint performance and preventing the occurrence of welded defects.
In the past, it has been the usual practice such that the proper number of passes for each layer is preset by the welder who measures the groove width of this layer visually or by means of any instrument and determines the proper number of passes prior to the welding of the layer and then the welding is performed by determining the tracing positions of the welding torch for each pass. Therefore, as far as such a method has been used, it is possible to realize an unattended automatic multi-layer welding and increase the welding efficiency.